The present invention relates to the field of spark plug containing engines. it deals with orienting the spark plug ground electrode in both flat and dome shaped piston engines to optimize performance and/or prevent the piston from hitting the ground electrode.
In dome shaped piston engines, the spark plug located near the edge of the cylinder must be oriented so that its ground electrode extends substantially away from the center of the cylinder, leaving the most space between the spark plug and top of the piston when the piston is at top-dead-center. Hence, such orientation prevents the piston from engaging the spark plug ground electrode at top-dead-center and either causing electrode damage or the plug gap to be varied. Top-Dead-Center "T-D-C" is that position of the piston when it extends farthest into the cylinder.
In the case of a flat piston engine, to improve efficiency, for example, the ground electrode should be pointed toward the center of the cylinder when the spark plug is tightly secured in its mooring in the cylinder head. Tests have indicated that engine efficiency has increased as much as 10 percent by such orientation. It is believed that the closer that the spark is in an unobstructed way to the intake valve the more efficient the engine appears to be.
Generally, orientation of each spark plug ground electrode, to obtain the aforementioned benefits, is had by trail and error. It is understood, of course, if each plug and each plug receiving hold were made standard with the same starting thread orientation trial and error orientation would not be necessary. However, the obverse is true. Electrode orientation in a domed shaped piston engine is accomplished, for example, by marking plural spark plugs on the exterior thereof with a "Magic marker" to show the direction in which the ground electrode points. Then each plug is threaded into a cylinder and tightened therein until one is found whereby its ground electrode points away from the center of the cylinder at approximately 90 degrees. Each cylinder of the engine is successively fitted with an appropriate spark plug in this manner. In the case of a flat piston engine this same procedure is performed except that the spark plug ground electrode for a respective cylinder must point toward the center of the cylinder and toward the valves.
The above technique of ground electrode spark plug orientation was and still is adequate, however, it is time consuming and one cannot store extra plugs without confusion. Some way has been needed to categorize or mate the plug for its respective cylinder. This need is met, in part, by using a threaded disk in which the plug is threadably inserted. Plural disks are used for plural cylinders. However, the disks can be lost and misplaced and the plug can be only hand tightened in the hole and thereby create inventory problems. In the case of an emergency whereby the matched plug is immediately needed, preparation error and loss of disks cannot be permitted. Hence, a long felt need has existed for a device and process whereby plural substitute plugs can be stored, and, inventoried at a glance.